One-half wave length resonant explosion gas unit



Feb. 3, 1953 J. H. ANDERSON EI'AL 2,627,163

ONE-HALF WAVE LENGTH RESONANT EXPLOSION GAS UNIT Filed Dec. 16, 1947 2Sl-iEE'IS-SPEET l THEIR ATTORNEY- Patented Feb. 3, 1953 ONEdiALF waveLENGTH RESONANT EXPLosmN GAS UNIT James H. Anderson, Easton, Pa., andGeorge Farnell, Phillipsburg, N. .L, .assignors to IngersolbRandCompany,'New York, N. 1., a cor-pprat on o w Jersey Application December16, 1947, Serial No. 792,066

sions at either of the points for cooling thelexhaust gases and thecasing of the explosion Qhamber.

A fur her bjec is tocon truct-a resonan esplosion chamber whichexplosions occur at point t t are a pr ximate on alf oi a explosion wavength anst thus allowi p e ur wa o an x l ion i the h mb r t compress asucceeding charge of explosive mixture therein.

Oth r obje i l be in a ob o and in part pointed out hereinafter.

In the accompanying drawingsin which similar efe ence n me a s r e osimilar par s! Figure fl s a side el vationo a gas turbine pla em d n an nt xplos n power unit onstructed in c o danc with he p actice o theinvention,

Figure 2 is alongitudinalview of the gas turbine plant, somewhatenlarged and partly'broken away,showing the positions of the controllingdevices when at rest, iqFigure 3 is a side elevation of a gas turbineplant showing a modified "form of the invention, Figure 4 is a viewtaken through'l 'igures along the line 4-4 and showing the position ofthe controlling devices when the power unit is at rest; and

Figure 5 is a top view, partlybroken away, of

a gas turbine plant-showingstill another modified format the invention.

Referring more particularly to the drawings, andat -firstto FigureLaresonant explosion gas '-turbine plant, designated in general by 20,is shown as includinga turbine 21!, a resonant explosion power unit 22for providing the operating .gasesgfor the turbine, and a compressorZS-driven by the turbine for delivering compressed air to :thelpoweruunit 22.

The compressorland turbine are shown ias being of $118 axial flow typeshaving their rotors 24 and '25 coaxiallyarranged with each other and theopposedends of thelrshafts 28 and -19 con- 0-33- 7 2 nected together bya coupling 30. On the other end of the shaft 29 is a coupling 3| whichserves as a power takeeofi for the turbine, and. theouter end of theshaft 28 is adapted to be connected with a clutch mechanism 32 which inturn is i litached to the operating shaft of a Starting motor 33. Anoperating lever arm 34 for the clutch mechanism 32 is pivoted at a pointon the base of the starting motor to make possible the en.- gagement anddisengagement of the clutch mechanism.

The resonant explosion power unit 22 com? prises a casing 35 which formsalchamber 3J5 having relatively spaced explosion zones 31 and 38,

' two in the example shown, and located adjacent the ends of the casing35. Compressed air is con.- vcyed from the compressor to theexplosionzones by a conduit 39 which leads to ports 40 and M in the end plates 26and 21 of the casing 35.

The flow of air through the ports 4-0 and M is controlled by pressureresponsive valves 42 and '43, respectively. The valves are shown asbeing Qf the poppet typ an th r st m 44 a hav n slidin f i rojecti s 4and in he ondu ilho val e 2 n -3 ar held ota- 1y unsea ed by sp n s 46 a41 ono ihs the valve stems and acting against the projectio 4 and 49 anthe a e u s nj ct d to th cha be y spray no zles 50 and iaoent th exploson ones 31 and 38, respectively, and the explosive mixtures a gnited .bype k plugs and 53 proi o nsint e c si n each i t t an verse plane ofthe-fuelspray nozzles. Fuel, under pressure, isconveyed from fuel pumps54 and 55 to the spray nozzles by conduits 56 and 51. The pistons 59 and60 of the pumps 54 and=55 are actuated by a crankshaft 6| and amotorqflin a well known manner for pumping fuel from the main fuel line 58alternately to the nozzles and 5|.

I he casing 35 comprises two cup-shaped members 63 and 64 having theirinner open ends spaced to provide adischai ge opening 65 for the exhaustgases. Surrounding this opening and lattachedto the casing is a housingring .66 which is so timed that, when the pressure wave irom anexplosion is at its peakin one end of the chamber, it willsimultaneously be at its lowest value in the other end of the chamberand, to

this end, the length of the chamber approximates one-half of a pressurewave length, or an odd multiple thereof. In other words, it is to benoted, when this condition exists within the chamber 36 the frequency ofexplosions at the opposite ends of chamber 36 will be equal to or afunction of the natural frequency of the easing which forms the chamber36. It is apparent then, from the foregoing discussion, that in order toobtain the proper frequency of explosions and the proper timing relationof these explosions with respect to the reflected waves, discussed morefully hereinafter, it is merely necessary to vary the frequency of theexplosionby controlling the speed of the motor 62 in any well knownmanner such as varying the voltage impressed on either the field or thearmature, or both, of the motor 62 until the aforesaid condition isobtained. These pressures can, of course, be measured by any well knowndevice (not shown).

For any given condition, that is, length of the casing 35and pressureand temperature of the gas within the chamber 36, there is a fixedfrequency or direct function of this frequency at which the power unit22 will operate most effectively. That is, under these given conditionsthe length of a pressure wave in the chamber 36 is determined by thelength of time it takes for the peak of the wave to travel along thecontainer and return to its point of origin. This time is, of course,dependent on the distance traveled (twice the length of the chamber 36)and the speed at which the wave travels (depending upon the pressure andthe temperature within the chamber 36). Inasmuch as the pressure andtemperature within the chamber 36 is dependent, in part, on the mixtureand type of fuel used and the size of the chamber 36, a practical methodfor obtaining the proper timing relation is facilitated by the expedientof measuring the pressure at the explosion end of the chamber 36 andigniting the explosive mixture during a period of maximum pressure atthat end. When this timing relation has been attained, the aforesaidcondition will be closely approximatednamely, maximum pressure at oneend of the chamber 36 and minimum pressure at the opposite end thereof.There will be a slight devia- -t'ion from this condition due to thedifference in velocity in the peak of the pressure wave and the troughof the pressure wavedue to the difference in pressure-however, thisvariation is not of sufficient magnitude to materially effect theoperationor the timing relation as herein set forth. 7

In furtherance of this cycle of operation or method of compressing agas, the end plates 26 and 21 of the casing serve as reflecting membersto reverse the pressure waves for return movement to their points oforigin.

At the beginning of an operating period of theplant, and at which timethe starting motor 33 is imparting rotary movement to the rotors 24 and25, air discharged by the compressor will flow into the ends of theexplosion chamber. If then, the fuel pump motor 62 is started fuel willbe injected into the air charge in the explosion zone 31, for example,through the nozzle 50 and the resulting explosive mixture is ignited atthe spark plug 52. This initial explosion forces the valve 42 to itsseat, thus cutting off further flow of compressed air through the port40, and the pressure wave of the explosion travels toward the oppositeend of the chamber 36 cans ing a low pressure area to exist in front ofthe valve 42 which permits the valve to unseat and admit a new charge ofair into the explosion zone 31. As the peak of the wave reaches theopposite end of the chamber 36 it further compresses the air in theexplosion zone 33, thus causing the valve 43 to seat in the port 4|.

When the peak of the pressure wave hits the end plate 21 of the casing,it is reflected back toward its point of origin. As it moves back alongthe chamber a low pressure area is created in the zone 38, thus allowinganother charge of air to be admitted thereinto. The peak of thereflected pressure wave hits the end plate 26 and is again reflected,this time toward the explosion zone 38 allowing a second charge of airto be admitted into the chamber through the port 40. The movement of thepeak of the wave toward the explosion zone 38 compresses the new chargeof air therein.

At the instant that the peak of the wave reaches the explosion zone 38,fuel is injected through the nozzle 5i into the compressed air, and thisexplosive mixture is ignited by a spark at the plug 55. A wave from thisexplosion moves toward the explosion zone 31 allowing the valve 43 toopen and compressed air to be admitted into the chamber. When the peakof this wave hits the end member 26, it is reflected back toward itspoint of origin. As the wave next approaches the explosion zone 38, thevalve 42 is again permitted to unseat and admit a third charge of airinto the explosion zone 31. After again reversing direction when hittingthe end member 21, the wave moves back toward the zone 31, compressingthe air therein which is then impregnated with fuel, and the resultingmixture is ignited. Thus, from this explosion another Wave is startedwhich continues through the same cycle of events. Timing of ignition ofthe explosive charges in the opposite ends of the chamber 36 may beaccomplished in any well known manner, as for example the manner shownin U. S. Patent 2,517,- 822.

It will be readily understood that each wave will travel approximatelyone and one half wave lengths before another explosion takes place inthe explosion chamber 36. Since successive explosions occur at oppositeends of the chamber, three separate charges of air will be drawn intoone explosion zone in the interval between explosions in that particularzone. All three of the charges are advantageous in cooling the exhaustgas and the walls of the casing surrounding the explosion, and the thirdis impregnated with fuel to form an explosive mixture.

In the instance where materials capable of withstanding extremely hightemperatures are used, the cycle could be so timed that the explosionswould occur at time intervals of one half wave length. Thus, the speedof the fuel pump motor 62 would be increased so that fuel would beinjected into each charge of air, and the speed of ignition would beincreased accordingly to ignite the resulting explosive mixtures,consequently enabling a large volume output of high temperature exhaustgases. In such a cycle, -.a pressure wave would move from the explosionzone 31 through a distance of one half a wave length to the zone 38 ofthe chamber 36, compressing a charge of explosive mixture which isimmediately ignited to set another wave in motion; toward the otherzone;3'lof thechamber. i j. .3. hat; o insz char es; :Qfgair would'b'eadmitted between I the charges 'ofexplosiveimixture. g

Another advantageous feature of .the invention is that the exhaust gaseswill pass from the middle of the chamber at practically a constantpressure and, therefore, without the pulsations which characterize theoperation in the other parts of the chamber. Successive explosions inthe explosion chamber produce pressure waves, which are 180 out of phasewith respect to time and are moving in opposite directions; thus theywill have the effect of constantly neutralizing each other at adistanceof one quarter of a wave length from the point of explosion, or any oddmultiple of one-quarter wave length. Since the length of the explosionchamber 36, in the form of the invention illustrated, is equal to onehalf of a wave length the exhaust gases are discharged from the middleportion of the chamber at a substantially constant pressure.

The modified form of the invention shown in Figures 3 and 4 comprises atubular casing having a U-shaped explosion chamber 36 and an air supplychamber 69 which are separated by walls or reflecting members 10 and Htherebetween. In the walls 10 and H are the air inlet ports 40 and 4|,respectively, having pressure responsive valves 42 and 43 adapted toseattherein to control the flow of air into the ends of the explosionchamber. The fuel injection and ignition devices are situated in thecasing 35 near the ends of the explosion chamber, and a dischargeopening 65 at the curve of the U allows the exhaust gases to pass fromthe chamber into the discharge conduit 68. This form of the invention isadvantageous in that it reduces the space requirement of the unit andmakes possible the use of shorter inlet and discharge conduits.

The modified form of the invention shown in Figure 5 differs from thosepreviously described mainly in that the casing 35 and, therefore, theexplosion chamber 36, is of circular shape in order to further minimizethe overall length of the explosion unit. The mode of operation of thisform of the invention and that disclosed in Figures 3 and 4 is identicalwith that described in connection with the form shown in Figures 1 and2, and it is to be understood that, in both instances, the length of theexplosion chamber approximates one half of a pressure wave length or anodd multiple of one half a wave length.

From the foregoing description, it will be apparent to those skilled inthe art that changes and modifications may be made without departingfrom the spirit of the invention or the scope of the claims.

We claim:

1. A resonant explosion power unit, comprising a casing forming anexplosion chamber the longitudinal axis of which is U-shaped, reflectingmembers on the casing to reverse the direction of movement of pressurewaves in the chamber and being approximately one half of an explosionwav length apart, air inlet ports situated in the reflecting members,valves to seat in the ports and acting responsively to the pressurewaves in the chamber for admitting charges of air thereinto, fuelinjection means so timed that fuel is introduced into every third chargeof air entering the chamber through each inlet port, means for ignitingthe resulting explosive mixtures in the ends of the chamber in equallyspaced intervals of time, and a discharge opening in the intermediateportion of the casing through which the exhaust gases are discharged.

' 2. A resonant explosion power unit, compris ing a casing having anexplosion chamber wherein the longitudinal axis of which is arcuate inshape, reflecting members to reverse the movement of explosion pressurewaves in the chamber and being approximately one half of an explosionwave length apart, said explosion chamber having explosion zonesadjacent the reflecting members of the casing, air inlet ports in thereflecting members, valves to seat in the ports and acting responsivelyto the pressure waves in the chamber for admitting charges of air intothe explosion zones, fuel injection means so timed that fuel isintroduced into every third charge of air entering each explosion zone,means for igniting the resulting explosive mixtures'in the explosionzones in equally spaced intervals of time, and a discharge opening inthe casing intermediate the two zones through which exhaust gases aredischarged at practically constant pressure.

3. A resonant explosion power unit, comprising a casing having anexplosion chamber and a discharge opening at the intermediate portionthereof, reflecting members on the casing serving to reverse themovement of explosion pressure waves in the chamber and beingapproximately one-half of a pressure wave length apart, said explosionchamber having explosion zones adjacent the reflecting members, meansfor introducing charges of air into the explosion zones, means forinjecting fuel into every third charge of air introduced into each ofsaid zones to form an explosive mixture, and means for igniting theexplosive mixtures at equally spaced intervals of time.

4. A resonant explosion power unit comprising a casing with a chambertherein having a length substantially equal to an odd multiple ofonehalf an explosion wave length, a discharge opening for the chamberlocated at substantially an odd multiple of one-quarter explosion wavelength from an end of the chamber, end members on said chamber forreflecting explosion pressure waves in the chamber thereby causingperiods of relatively high and low pressure at the ends of the chamber,a valve at each end of the chamber for admitting air thereinto inresponse to such variations in pressure, each of aid valves beingarranged to admit a charge of air into the end of the chamber with whichit is associated during each low pressure period at such end, fuelinjection means at each end of the chamber for injecting fuel into oneof a plurality of successive charges admitted into each end of thechamber between explosions, and means for igniting the explosive mixtureresulting from such injection of fuel.

5. A resonant explosion gas unit comprising a casing with a chambertherein having a length substantially equal to one-half of an explosionwave length, a discharge opening in the chamber located at substantiallythe midpoint of the chamber, end members on said chamber for refleetingexplosion waves in the chamber thereby causing periods of relativelyhigh and low pressure at the ends of the chamber, valve means at eachend of the chamber for admitting air thereinto in response to suchvariations in pressure, each of said valve means being rranged to admita charge of air into the end of the chamber with which it is associatedduring each low pressure period at such end, fuel injection means ateach end of the chamber for injecting fuel into every third chargeadmitted into each end of the aea'mea chamber, and meansforigniting-the. explosive length from an endof the chamber; end membersonsaid chamber for reflecting:explosive-waves in the-chamber: therebycausing periods of relatively high and low pressure. at; the: ends of:the" cham? ber, valvesa-t: the; ends. of the. chamber for. admitting:successive charges; of air thereinto in reg.-' sponserto: suchvariations inpressure, fuelinjection means: at. each end of the.chamber. for, injecting" fuel into the chamber to; formexplosivecharges. of fuel and air therein, and. means t each; endof thechamber for ignitingthe explosive charges. andbeing timed to ignite:such charges I during successive third periods of relatively highpressure at each end. of the chamber.

7. A resonant explosion power unit comprising acasing with achambertherein having. a length substantially equal to an odd multiple. ofonecharges. of" fuel and. airtherein. and; means-. at each end of thechamber for igni he 811ml;vexplosive. mixtures and being.- timed:relative to the end. of? the. chamber with: which it 2 8 0? ciated toignite. such mixture; during" successive: third .periodszof relativelyhigh ressurezandlbeing; timed relative to the. other end; ofthe,chambersuch; that: ignition, occurs. alternatively at; the.oppositeendsof the. chamber at equally; spaced intervalsi.

JAMES H; AN ERSON, GEORGE FARNELL.

REFERENCES CITED The following references: are of record in the fileof'this-patent:

UNITED STATES PATENTS Number Name. Date-- 1,036,288 Matricardi; Aug;20,1912 1,415,780 Bowen May 9,..1922 1,726,491 Johnson l- Aug. 27,.1929; 2,275,756. Hanson Mar. 10, 1942 2,396,068 Young ash Mar. 5,, 1946.2,427,845 Forsyth Sept. 23,,1-947 2,480,626 Bodine: .Aug, 30, 19492,493,873 Hill- Jan. 10,1950 2,503,584 Lipkowski Apr. 11-, 19.50.2,523,379 Kollsman Sept. 26, 19.50, 2,546,966 Bodine i Apr..3, 19,512,550,515 Anderson Apr. 24, 19.51

FOREIGN PATENTS Number Country Date 27,724. Great Britain Dec. 16,190.?176,838 Great Britain Mar. 6; 1.922. 138,642. Great. Britain Nov...29,1923

